Pre-cast concrete storage structure

ABSTRACT

A variety of storage structures may be constructed onsite entirely from pre-fabricated parts reducing labor and time required for assembly.

CROSS-REFERENCED TO RELATED APPLICATIONS

This application is a continuation-in-part of a non-provisional application Ser. No. 15/950,412, filed Apr. 11, 2018, which is also deemed incorporated by reference in its entirety in this application.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

BACKGROUND OF THE INVENTION I. Field of the Invention

The present invention relates to storage structures and, more particularly, to storage structures made from pre-cast or pre-stressed concrete components.

II. Discussion of the Prior Art

Since ancient times, various storage structures have been employed. For example, for decades, if not centuries, silos have been used for the storage of corn and other grains. Silos have also been used to store silage, manure intended to be used as fertilizer, and other agricultural products. For at least the last one hundred years, there has been an increased demand for a low-cost durable silo structure. Various manufacturing methods have been employed for making silos, but these methods have not resulted in any substantial reduction in the cost of materials, labor to complete construction of the silo or in any significant advantages with respect to ease of construction. To this day, there continues to be a need for silos that are sufficiently strong to withstand the elements, inexpensive to manufacture, less laborious to manufacture, quicker to assemble on site, primarily assembled at ground level, and simple to build, move, disassemble and rebuild when desired.

Ideally, most of the components of the silo should be built in a controlled environment such as a factory to maintain better working conditions, better quality control and more consistent production to specifications. Likewise, the components should be adapted to be assembled using a crane to eliminate manual handling of components at considerable heights. Ideally, the number of components that must be assembled at the assembly site should be limited in number and in type to simplify assembly and the time required to complete the assembly.

SUMMARY OF THE INVENTION

Virtually all of the foregoing problems with prior art storage structure designs and all of the foregoing desirable characteristics for such a structure are achieved by providing a storage structure made from a plurality of semi-circular wall panels each made of pre-cast or pre-stressed concrete in a controlled environment and then transported to the job site for final assembly of the storage structure. Each of the semi-circular wall panels have a first horizontal planar surface with a groove formed therein, a second horizontal planar surface with a tongue projecting therefrom, a first planar end surface extending between the first and second horizontal planar surfaces with a groove formed therein, and a second planar end surface extending between the first and second horizontal planar surfaces with a tongue extending therefrom. The semi-circular wall panels are adapted to be arranged in a plurality of hollow circular layers. Each hollow circular layer comprises a set of the semi-circular wall panels and further comprises first tongue and groove joints between immediately adjacent semi-circular wall panels of the set. These first tongue and groove joints each comprise a tongue extending from the second planar end surface of a semi-circular wall panel and a groove of the first planar end surface of an immediately adjacent semi-circular wall panel.

After assembly of the hollow circular layers on the ground, a crane can then be used to create a hollow vertical stack of the hollow circular layers. The hollow vertical stack of the hollow circular layers comprises second tongue and groove joints between immediately adjacent hollow circular layers in the stack. The second tongue and groove joints each comprise a tongue extending from the second horizontal planar surface of a semi-circular wall panel of a hollow circular layer and a groove of the first horizontal planar surface of a semi-circular wall panel of an immediately adjacent hollow circular layer of the stack.

As noted, it is beneficial to reduce the number of parts that need to be assembled at the job site. It is also necessary to lock the first and second tongue and groove joints. As such, a plurality of joint locks is provided. These joint locks are arranged to fix together the adjacent semi-circular wall panels of each hollow cylindrical layer and are also used to fix together the adjacent hollow circular layers of the vertical stack. The joint locks provided also allow the joints between the semi-circular wall panels of a hollow circular layer to be offset when forming the stack from the joints between the semi-circular wall panels of an immediately adjacent hollow circular layer.

The number of parts to be assembled at the job site is reduced by providing locks that comprise rows of internally threaded inserts embedded in each of the semi-circular wall panels adjacent the tongues and grooves of the panels. Each lock further comprises at least one bridging plate adapted to extend across the tongue and groove joint formed between two immediately adjacent semi-circular panels. These bridging plates are further adapted to be attached, using bolts, to the internally threaded inserts of the two panels proximate the tongue and the groove joint to be locked.

Alternative lock arrangements may be used to further reduce the number of parts. For example, the bridging plates may be integrally formed with or permanently attached (such as by a weldment) to an insert of one panel. Another insert embedded in the concrete of an adjacent panel and forming a portion of the joint lock can be provided with a threaded fitting. A single bolt can then be used to couple the bridging plate to this insert to lock together the joint bridged by the bridging plate.

The bolts of the joint locks may be eliminated altogether. For example, one half of the joint lock may be a bridging plate integrally formed with or permanently attached at one end to an insert embedded in the concrete of a first panel. The other half of the lock may be a pocket permanently attached to an insert embedded in the concrete of a second panel. The pocket is adapted to receive and be the other end of the bridging plate. The bridging plate and pockets are provided with at least one stop and at least one catch to ensure that the bridging plate does not inadvertently become decoupled from the pocket after the joint has been locked.

Any of the foregoing locks can be used to lock together the set of semi-circular wall panels used to form a hollow circular layer. Likewise, any of the foregoing locks can be used to lock together adjacent hollow circular layers of the vertical stack.

In certain cases, it will be advantageous to support the vertical stack on a base. In such cases, the base may also be made of pre-cast concrete and have a top surface adapted to form tongue and groove joints with each of the semi-circular panels used to form the bottom-most hollow circular layer of the vertical stack. Base locks adapted to fix together the bottom-most circular layer of the vertical stack to the base may be provided. These base locks may each comprise a first plate embedded in a semi-circular wall panel of the bottom-most circular layer of the vertical stack and a base plate embedded in the base. A bridging plate may also be provided. This may be a separate L-shaped plate or may be integrally formed or welded to either the first plate of the semi-circular wall panel or the base plate embedded in the base. A fastener, such as a bolt, may be used to couple the bridging plate to the other of the base plate and the first plate.

To prevent rain, snow, or the like, from entering the storage structure, the storage structure will typically be provided with a roof. The roof is adapted to be mounted to the upper-most hollow circular layer of the stack. Again, tongue and groove joints are formed between each of the semi-circular wall panels used to form the upper-most hollow circular layer of the vertical stack and the roof. Roof locks are arranged to fix together the roof tongue and groove joints. The roof locks each comprise a first plate embedded in the semi-circular wall panel, a roof plate embedded in the roof and a bridging plate adapted to be fixed to both the first plate and the roof plate.

The roof itself may be formed of a plurality of roof panels also joined together by tongue and groove joints and locked together by roof panel locks similar in design to the locks described above. These roof panels may be made in a controlled environment out of pre-cast concrete or pre-stressed concrete. At the time the panels are manufactured, the internally threaded inserts of the locks are embedded in the concrete adjacent the tongues and the grooves, as was the case with the other embedded treaded inserts discussed above. Bringing plates then span the joint and are bolted to threaded inserts of the two roof panels on opposite sides of the joint to secure the joint.

For the structure described above to be used for storage, the hollow interior must be accessible from the outside. As such, one or more access openings are provided in the structure and doors moveable between open and closed positions are associated with each of the access openings. For example, the structure can include an upper access opening adapted to be used to fill the structure and a lower access opening adapted to be used to empty the structure.

Various seals may be employed at each of the joints, to prevent, for example, infiltration of moisture during periods of inclement weather. These seals may be semi-permeable to prevent the passage of liquids through the seals, while at the same time permitting gasses to pass through the sealing members.

All the pre-cast components described above are formed in a controlled environment and then transported to a job site. At the job site, a crane is used to assemble the various layers of the stack and also to assemble the roof to the stack. Thus, it is important that some means be provided to couple the crane to the various components during the assembly process. Thus, separate lifting brackets may be provided. These lifting brackets may include components embedded in the pre-cast concrete elements to be assembled. Alternatively, they can be temporarily attached to the embedded elements of the locks. For example, the plates 43 attached to the tops of the panels may first serve as lifting brackets, and later as bridging plates.

It is, of course, important that the structure be durable and not susceptible to damage from weather or from interaction of the interior surfaces of the structure with the contents of the structure. From the foregoing, one will appreciate that the semi-circular wall panels each have a concave inner surface. It may prove desirable to treat the concave inner surface (or the entire panel) with an anti-corrosive material. Likewise, it may be desirable to treat the exterior of the structure with a paint, sealant, or the like, to protect the structure from the elements. This last step is often not functionally necessary, particularly when the concrete is formulated properly but may be desirable for aesthetic reasons given the durability of concrete in most weather conditions. Such formulations are well known in the art and will not be discussed in further detail here.

The concrete panels, base and roof are all typically reinforced using a wire mesh or rebar. These components should be fully embedded in the concrete and not exposed since, if exposed, such components can rust, thus causing deterioration of the structure.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, especially when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts:

FIG. 1 is a plan view of a multi-layered storage structure made in accordance with the present invention;

FIG. 2 is a top view of a semi-circular concrete wall panel used in the construction of the circular layers of FIG. 1;

FIG. 3 is a cross-sectional view through line 3-3 in FIG. 2;

FIG. 4 is a bottom view of a circular layer made from semi-circular panels of the type shown in FIGS. 2 and 3;

FIG. 5 is a plan view of a multi-layered storage structure made in accordance with the present invention showing the location of locking assemblies used to lock various concrete components together;

FIG. 6 shows an assembly of horizontal and vertical lengths of rebar and locking members welded to the rebar embedded in the concrete panels of FIGS. 2-3;

FIG. 7 is a cross-sectional view illustrating a locking assembly locking a tongue and groove joint between two semi-circular concrete wall panels of the type shown in FIGS. 2 and 3;

FIG. 8 is a plan view of a hole through one of the bridging plates of one of the lock assemblies;

FIGS. 9 and 10 are cross-sectional views showing how a bolt passing through the hole of FIG. 8 is used to couple the bridging plate to a locking member embedded in the concrete of one of the concrete panels of the present invention;

FIG. 11 is a plan view of the concrete roof panels made in accordance with the present invention;

FIG. 12 is a cross-sectional view through line 12-12 in FIG. 11;

FIG. 13 is a cross-sectional view through line 13-13 in FIG. 11;

FIG. 14 is a cross-sectional view through line 14-14 in FIG. 10;

FIG. 15 is a top plan view of a roof of a storage structure made in accordance with the present invention showing the arrangement of the lock assemblies used to lock the tongue and groove joints between the panels of FIG. 10 together;

FIG. 16 is a side plan view of the roof of FIG. 11 after the panels have been assembled showing the arrangement of the lock assemblies used to lock the tongue and groove joints between the panels of the roof of FIG. 11 with the top circular layer comprising the semi-circular concrete wall panels illustrated in FIG. 5;

FIG. 17 is a perspective view showing a partially assembled stack of modified panels with several left out of the stack so that both the inside and outside of the stack are visible;

FIG. 18 is a partial perspective view of the stack shown in FIG. 17 illustrating the tongue and groove joints employed to assemble the stack of modified panels shown in FIG. 17;

FIG. 19 illustrates bands and clamps being employed to secure together the modified panels of FIG. 17 into a layer;

FIG. 20 is a more detailed view of an exemplary band clamp that may be used when securing together into a layer of modified panels of the type shown in FIG. 17;

FIG. 21 is a perspective view showing an alternative clamp;

FIG. 22 is a perspective view showing an alternative panel design.

DESCRIPTION OF THE PREFERRED EMBODIMENT

This description of the preferred embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. In the description, relative terms such as “lower”, “upper”, “horizontal”, “vertical”, “above”, “below”, “up”, “down”, “top” and “bottom” as well as derivatives thereof (e.g., “horizontally”, “downwardly”, “upwardly”, etc.) should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms such as “connected”, “connecting”, “attached”, “attaching”, “join” and “joining” are used interchangeably and refer to one structure or surface being secured to another structure or surface or integrally fabricated in one piece, unless expressively described otherwise.

Storage structures such as silos, grain bins, manure tanks and the like (see e.g., FIGS. 1 and 5) can easily be manufactured on-site using pre-cast/pre-stressed concrete panels 4 of the type shown in FIGS. 2-4. Each concrete panel 4 is semi-circular and has a concave interior surface 6 and a convex exterior surface 5. Defining the top and bottom of each semi-circular panel 4 are first and second horizontal planar surfaces 16 and 18. As shown, the bottom horizontal planar surface 16 has a groove 17 formed thereon. A tongue 19 extends from the top horizontal planar surface 18. Defining the ends of each semi-circular concrete panel 4 are first and second vertical planar end surfaces 20 and 22. As shown, the first planar end surface 20 extends between the first and second horizontal planar surfaces 16 and 18. The first planar end surface 20 has a groove 21 formed therein. The second planar end surface 22 also extends between the first and second horizontal planar surfaces 16 and 18. The second planar end surface 22 has a tongue 23 extending therefrom. In alternative embodiments, the position of the groove and tongues on either the first and second horizontal surfaces 16 and 18 or the first and second planar end surface 20 and 22 may be reversed without deviating from the invention.

A plurality of identical semi-circular concrete panels 4 are ideally mass produced within a controlled environment (such as a factory) which typically will be off-site. The panels 4 are molded in forms. For manufacturing efficiency, there should be enough forms so that full loads of mixed concrete can be used at the same time when forming the panels 4. The environment is controlled for both humidity and temperature to ensure efficient and proper curing of the concrete used to make the panels.

The forms are adapted to receive and hold in position rebar and/or a wire mesh employed to reinforce the concrete panels 4. See FIGS. 6 and 7. The mold is further designed to ensure that the rebar, or mesh, are not exposed in the finished panels. The mesh includes a plurality of horizontally extending sections of rebar 27 and a plurality of vertically extending sections of rebar 28.

The horizontally extending lengths of rebar 27 and the vertically extending lengths of rebar play another significance in the present invention. At intersections of the pieces of rebar 27 and 28 immediately adjacent the periphery of each panel, locking sleeves 24, 25 and 26 coupled to the rebar mesh prior the rebar mesh being inserted into a mold. Each locking sleeve 24, 25 and 26 is a hollow, open-ended fitting (e.g., a tube) with internal threads adapted to receive a bolt at each end. The internal threads of the locking sleeves engage external threads of the two bolts 48, as shown in FIG. 7.

It is important that during the molding operation that the open ends of sleeves 24, 25 and 26 do not become covered with concrete. As such, bolts are coupled to each end of each of the sleeves 24/26 prior to molding of the concrete. Most typically, the bolts are used to attach pocket-forming plates (not shown) to the opposing ends of sleeve 24. Likewise, pocket-forming plates are to the opposing ends of sleeves 25 and 26 using bolts prior to molding. After molding, these bolts and plates are removed leaving behind in the concrete shallow pockets 27 (see FIG. 4) adapted to be aligned and receive a bridging plates (discussed further below) so that, when attached, the bridging plates are flush with the exterior convex surface 5 and concave interior surfaces 6 of the panels.

The forms used to mold the panels 4 are further adapted to provide the grooves 17 and 21 and the tongues 19 and 23. The locking sleeves 24, 25 and 26 are embedded in the concrete when forming the panels 4.

After the panels 4 have been manufactured as described above, a sufficient number to assemble the desired storage structure are delivered to the site where the storage structure is to be erected. Upon arrival at the job site, the panels are unloaded and arranged in groups or sets. Each group or set consists of the requisite number of semi-circular panels 4 required to make a hollow circular layer 40 a-n.

To make layer 40 a, for example, a set of panels 4 are arranged in a circle and tongue and groove joints are formed between immediately adjacent panels by coupling the grooves 21 of the first planar end surface 20 of each of the panels 4 with the tongues 23 extending from the second planar end surfaces 22 of the immediately adjacent panels 4. See, e.g., FIG. 4.

To stabilize the tongue and groove joints formed by the tongues 23 and grooves 21, a first set of joint locks 42 are employed. These joint locks 42 comprise the locking sleeves 24 and 26 referenced above and exterior bridging plates 45 and interior bridging plates 46 extending across the tongue and groove joints comprising tongues 23 and grooves 21. The bridging plates also reside within the pockets 27 for added strength and they provide the structures on the relatively smooth exterior and interior walls. Each of the bridging plates 45/46 is adapted to be coupled to a lock sleeves 24 on one side of the tongue and groove joint and lock sleeves 26 on the other side of the joint. This coupling can be done using bolts 48 extending through the bridging plates 45/46 and threaded into threaded fittings (orifices) in sleeves 24 and 26. Alternatively, the bridging plate 45/46 may be integrally formed with or welded to the lock sleeves on one side of the joint to reduce the number of bolts 48 required. Further still, and to eliminate the bolts altogether, the bridging plates 45/46 may not only be welded or integrally formed with one of the locking sleeves on one side of the joint, but may also incorporate a catch. The locking sleeves on the other side of the joint may be integrally formed with or coupled to a metal structure such as a pocket adapted to receive the bridging plate and having a stop surface adapted to engage the catch to prevent decoupling of the bridging plate from the pocket.

As assembly of the layers 40 a-n is completed on the ground, the layers are further assembled to form a stack 41. When forming the stack 41, it is advantageous to offset the tongue and groove joints of one layer (e.g., 40 a) from the tongue and groove joints of the immediately adjacent layers (e.g., 40 b), as shown in FIG. 5. As such, the layers are joined together as follows. With a first lower layer 40 a in position, a second layer 40 b is hoisted above the first layer 40 a and aligned so the joints of the second layer 40 b are between the joints of the first layer 40 a. The second layer 40 b is then lowered to form tongue and groove joints between the top horizontal planar surfaces 18 of the panels 4 of the first layer 40 a and the bottom horizontal planar surfaces 16 of the panels 4 of the second layer 40 b. More specifically, as the second layer 40 b is lowered into position, the tongues 19 of the first layer 40 a are received with the groove 17 of the second layer 40 b.

Gravity and joint locks 43 ensure the joints between the panels 4 of the two adjacent layers (40 a and 40 b) do not come apart. The joint locks 43 used are similar in design to those described above. More specifically bridging plates are coupled to lower locking sleeves 25 of the panels 4 of the second layer 40 b and also to upper locking sleeves 25 of adjacent panels 4 of the first layer 40 a. If the bridging plate 44 is designed accordingly, a single bridging plate 44 can be used to couple locking sleeve together to secure both a vertically extending tongue and groove joint between two adjacent panels 4 of a layer 40 a or 40 b and also the horizontally extending tongue and groove joints between adjacent layers 40 a and 40 b. Bolts 48 are used to make the necessary connections between the locking sleeves and the bridging plate(s).

Assembly and stacking of layers continues as described above until the stack reaches the desired height. The stack 41 may be supported on the ground in a variety of ways. One way is to provide a pre-cast/pre-stressed concrete base 60 (see FIGS. 1 and 5) made in the controlled environment of a factory and shipped to the job site. Base 60 is typically supported by footings 66 extending below the frost line. See FIG. 1.

Alternatively, the base can be installed below the frost line in which case, the bottom-most layers of stack 41 will be at least partially below ground level. The base 60 may be of any shape but dimensionally should be equal to or wider than the diameter of the bottom circular layer 40 a in all directions. As shown, the base 60 may be provided with a tongue extending upwardly and adapted to form a tongue and groove joint with the groove 17 in the bottom horizontal planar surface 16 of the panels 4 of the lower-most hollow circular layer 40 a.

To provide additional support to the stack 41, various base joint locks 62 are provided, as shown in FIG. 5. The base joint locks comprise locking sleeves 24, 25 and 26 embedded in the concrete of the panels 4 of the lowermost layer 40 a of the stack 41. The base joint locks 62 further include base bridging plates embedded in the concrete of base 60. The base bridging plates may have two sections formed at substantially a right angle with respect to each other so that one section is adapted to be bolted or welded to, or embedded in the concrete of, the base 60 and the other section is adapted to be bolted to one or more locking sleeves 24, 25 and 26 embedded in the concrete of the panels 4 of the lowermost layer 40 a of stack 41.

A pre-cast/pre-stressed concrete roof 70 may also be manufactured in the controlled environment of a factory and then shipped to the job site for installation on the top of stack 41. The roof may be formed as a single piece or may be formed in separate pieces assembled at the job site, as shown in FIGS. 11-14. In FIG. 11, the roof 70 is assembled from three separate concrete roof panels 71, 72 and 73. As shown, the two outer roof panels have interior planar surface 74, 76 each with a tongue 75, 77 formed thereon. Each also has a bottom surfaced 78 with a radial groove 79 formed therein. The center roof panel 72 has opposing planar surfaces 80/82 with grooves 81/83 forming therein. The center roof panel 72 also has a bottom surface 84 with a pair of grooves (not shown), one near each end. The grooves are positioned to be aligned with grooves 79 during assembly of the roof sections.

When roof panels 71, 72 and 73 are assembled, the interior planar surface 74 of roof panel 71 is brought into face-to-face registration with planar surface 80 of the center roof panel 72 and a tongue and groove joint is formed, by tongue 75 and groove 81. Similarly, the interior planar surface 76 of roof panel 73 is brought into face-to-face registration with planar surface 82 of the center roof panel 72 and a tongue and groove joint is formed by groove 83 and tongue 77. Joining roof panels 71, 72 and 73 together in this fashion also serves to create a circular groove comprising the radial grooves 79 of the outer roof panels 71 and 73 and the aforementioned grooves in the bottom of the center roof panel 72. This circular groove in the bottom of the roof forms tongue and groove joints with the tongues 19 extending from the top horizontal planar surfaces 18 of each panel 4 of the uppermost layer 40 n of stack 41.

Roof locks are employed to secure the tongue and groove joints of the roof. The roof locks comprise section connecting sleeves (similar to sleeves 24 and 26) embedded in the concrete and coupled to the reinforcing rebar of each of the roof panels. The roof locks further comprise bridging plates 90 adapted to extend across a tongue and groove joint between two of the roof panels and be coupled to the connecting sleeves of two adjacent roof panels (i.e., either roof panels 71 and 72 or roof panels 72 and 73). The roof locks further comprise L-shaped roof connecting plates 92 having a first section welded to the rebar and embedded in the concrete of the roof sections 71, 72 and 73 and a second section extending downwardly from the first section and adapted to be coupled to one or more of the locking sleeves 24, 25 and 26 at the top of the panels 4 of the uppermost layer 40 n using bolts.

Various features will typically be added to the basic structure described above. As shown in FIGS. 1 and 5, a railing is coupled to the roof 20. The railing is coupled to the roof via fitting 94 bolted to sleeves embedded in the concrete of the roof panels (see FIG. 16).

The structure would be of little use for temporary storage of grain, fertilizer, manure, silage, animal feed, fuel, water or anything else if there was no way to gain access to the interior space surrounding the structure. Therefore, various access openings are provided. In FIG. 1, an upper access opening 100 and a lower access opening 103 are shown. Each is equipped with a door 102/104 that can swing open to provide access, or swing closed to seal the interior chamber of the structure.

Also, it is well known that even the tightest of joints are susceptible to leakage. This is particularly true when a liquid or other fluidized material is to be stored in the storage structure. Therefore, various seals may be employed at the joints to prevent such leakage. In some cases, it is desirable to prevent liquids or other small particulate solids from passing through the joints, but to permit gases to pass through the joints (e.g., gases generated from the decomposition of matter stored in the structure). In such cases, the seals may be in the form of a gasket, O-ring, membrane caulk or the like which is semi-permeable.

There are, of course, other ways to exchange gases between the interior and exterior of the chamber within the structure, such as by opening the door or providing various vents such as vent 112.

While concrete is both durable and has superior weather resistance characteristics as compared to other building materials, it may be desirable to store within the storage structure materials that adversely affect concrete. Some chemical environments can quickly deteriorate even concrete of the highest quality. Acids, salts, alkalis and sulfates all aggressively deteriorate concrete. Manure will typically oxidize in air to form acids that attack concrete. Thus, the interior surface of the structure may be lined or coated with a protective material. For example, the concave interior surfaces 12 of the panels (or even the entirety of the panels) may be treated with an anti-corrosive material in the controlled environment of the factory. Over time, acid rain and other pollutants may have a deleterious effect on the concrete. Likewise, any water infiltration, together with freezing and thawing, can damage the concrete. To protect the structure further, or for aesthetic reasons, the exterior of the structure may be painted.

Various fixtures and fittings may be fixed to the structure. Examples include light sources to illuminate the interior or exterior of the structure, sources of heat and water, sensors, controllers, and status indicators. Sensors may be used, for example, to determine the internal temperature of the structure, the internal pressure of the structure, the presence of certain hazardous compounds (e.g., carbon monoxide or ammonia) within the structure, the condition of the doors 101/103 or vents 112, how full the structure is, or the condition of equipment used to fill or empty the structure. These signals may be sent from the sensors to a controller which processes these signals and, in response thereto, may display information on a display, illuminate warning lamps or otherwise convey important information to an operator electronically via text messaging or e-mail.

An important, but subtle, aspect of the present invention is the design of the holes in the bridging plates. As shown in FIG. 8, each hole 54 is surrounded by a tapered wall 56 and the opening 58 through which the shaft 52, bolt 48 passes is not round and is offset from the center of the top of the tapered wall 56. As shown in FIGS. 9 and 10, the head 50 of the bolt 48 is also tapered. As such, there is some play allowing the shaft 52 to begin to mate with a sleeve 26 (or a sleeve 24 or 25). As the bolt 48 is completely tightened, the tapered head 50 interacts with the tapered side wall 56 of the hole to secure the bridging plate 45 in the proper position. Typically, the installer will start all of the bolts used to secure the bridging plate 45 to the adjacent panels and then tighten them down in an alternating pattern. To secure the bridging plate 45 to lock the tongue and groove joints.

Further, the locking sleeves 24, 25 and 26 perform at least three important functions. In chronological order, the sleeves first are used to secure the pocket-forming plates as the concrete is molded in forms. Next, the sleeves are used to secure lifting fixtures to the panels. The lifting fixtures are adapted to permit a crane to lift the panels (or the assembled layers) and roof into position. Finally, the sleeves are used to connect the bridging plates to lock the joints of the structure.

The panels 4 and various clamps shown in FIGS. 1-16 offer numerous benefits during and after assembly. However, those panels 4 are very heavy. The are also costly and difficult to manufacture. The panels 100 shown in FIGS. 17-22 weigh significantly less and are also less expensive and easier to manufacture than the panels 4 shown in FIGS. 1-16.

The panels 100 have numerous features in common with the panels 4. The panels 4 and 100 are semi-circular. The panels 4 and 100 are manufactured of concrete in a mold or form. The concrete is poured into the mold or form after rebar, rewire or some other reinforcing structure has been placed in the mold and the concrete encapsulates the reinforcing structure so that it is not exposed once manufacturing of the panel is complete.

The panels 100 and the panels 4 are also similar because they have a top portion terminating in a first horizontal planar surface and a bottom portion terminating in a second horizontal planar surface. Panels 100, like panels 4, also have two end sections. A first of these end sections terminates in a first planar end surface and the second of these end sections terminates in a second planar end surface. The first planar end surface and the second planar end surface each extend between the first and second horizontal planar surfaces. As is the case with panels 4, the panels 100 each have a tongue extending from one of the first and second horizontal planar surfaces. Typically, the tongue will extend from the first horizontal planar surface at the top. Likewise, the panels 100, like the panels 4, each have a groove recess from the other of the first and second horizontal planar surfaces. As is the case with the panels 4, the panels 100 also each include a tongue extending from one of said first and second planar end surfaces and a groove recessed in the other of the first and second planar surfaces.

Sets of the panels 100, like sets of panels 4, are adapted to be formed into hollow circular layers with the tongue extending along a planar end surface of each panel forming a tongue and groove joint with the groove recessed in a planar end surface of the adjacent panel.

Like the layers made using the panels 4, the layers formed using the panels 100 may also be stacked. As the layers are stacked, the tongues extending from, for example, the first horizontal planar surfaces of the panels of a lower layer form a tongue and groove joint with the grooves in the second horizontal planar surfaces of the panels of the immediately vertically adjacent layer. Panels 4 and 100 are also similar because they each have a smooth inner surface or wall.

Like panels 4, the panels 100 are used to form a plurality of hollow layers, each of the layers assembled at ground level and adapted to be lifted to arranged the layers in a vertical stack to create a storage structure.

There are also significant differences between panels 4 and 100 that make panels 100 considerably lighter and also considerably less expensive in terms of material cost to manufacture. While the inner concave surface 102 of each panel 100 is smooth, the profile of the outer convex surface 104 of each panel 100 is not. More specifically, the panels 100 are not of generally uniform thickness.

As best illustrated by FIG. 22, each panel 100 has a thinner inner portion 106 framed by a thicker top portion 108 terminating in the first horizontal planar surface 18, a thicker bottom portion 110 terminating in the second horizontal planar surface 16, a first thicker end section 112 terminating in the first planar end surface 21, and a second thicker end section 114 terminating in the second planar end surface 22. Employing a thinner inner section 106 reduces the amount of concrete required to fabricate each panel, thus reducing the weight of the panel and material costs.

In some embodiments, it is advantageous to add one or more vertical ribs 120 to the thinner inner section 106. In FIGS. 17 and 22, each panel includes five such ribs 120. While ribs 120 add to both weight and material cost, the panels 100 are still considerably lighter and less expensive to manufacture than the panels 4.

The cost of manufacturing the panels 100 is also lower than the cost of manufacturing panels 4 for other reasons. One such reason is that no connecting brackets or plates are embedded in the concrete of the panels 100. Another is that no channels for bolts are created in the concrete during construction of the panels 100. The cost of such brackets and plates is eliminated. The time required to properly position such plates and brackets is eliminated. The time to position channel yielding inserts in a mold prior to filling the form or mold with concrete is also eliminated.

Instead of using such brackets and plates embedded in the concrete to lock the panels together, straps (i.e., bands) 130 and strap clamps 140 are employed as generally shown in FIG. 19. As shown in FIG. 19, ten straps 130 each surround the set of panels 100 assembled to form the bottom layer. Clamps 140 firmly secure the two ends of each strap 130 together and the straps 130 about the panels 100. A fewer number of straps 130 and clamps 140 may be employed to retain the panels 100 of higher layers of the stack because less outward pressure is exerted on the panels 100 near the top of the stack. The number of straps and clamps will also vary based on factors such as the material from which the strap is made, and the width and thickness of each strap.

As shown in FIG. 22, each of the vertical ribs 120 and the thicker end sections 112 and 114 may be provided with a plurality of recesses 122 open to the exterior and extending horizontally. These are aligned and adapted to receive the bands 130 as they surround the layer of panels. This serves to provide a locking force both horizontally and vertically when the clamps 140 are applied. More specifically, the straps and clamps not only resist outwardly directed forces after assembly of the structure, but also resist the vertical force of gravity as the layers of panels 100 are lifted into place.

The straps 130 are preferably made from a material that will not deteriorate when exposed to environmental conditions or due to contact with the concrete of the panels. One such material is stainless steel. Alternatively, the strap can be made of a material to which a protective coating is applied.

As shown in FIG. 20, each strap 130 has a main body portion 132 and a pair of end portions 134 and 136. The end portions 134 and 136 extend from the main body portions at a selected angle, e.g., ninety degrees. One or more gussets 138 may be employed to maintain the selected angle between the main body portion 132 and the end portions 134/136.

The strap (band) clamp 140, shown in FIG. 20, comprises a bolt 142 having a shaft extending through the end portions 134 and 136 of strap 130. A nut 144 is coupled to the bolt 142. Two spacers/elongated washers 146 and 147 are also shown. Spacer 146 surround the bolt's shaft and resides between the head of the bolt 142 and end portion 134. Spacer 147 surrounds the bolt shaft and resides between nut 144 and end portion 136. Tightening the nut 144 onto the bolt 142 serves to fasten the two ends 134 and 136 of the strap 130 together and the strap 130 firmly about the layer formed by the panels 100. Of course, other clamps may be used to fasten the ends of the strap together without deviating from the invention. The length of the strap will, of course, be dictated by the outer diameter of the layer formed by a set of panels.

An alternative strap and clamp arrangement is shown in FIG. 21. In FIG. 21 each strap 130 is a flexible wire or cable having a main body portion 132 and a pair of end portions 134 and 136. The end portions 134 and 136 of the strap 130, shown in FIG. 21, are threaded. The clamp 140, shown in FIG. 21, comprises a block 150 and two nuts 152, 154. The block 150 has top and bottom channels adapted to receive the end portions 134, 136 of strap 130. End portion 134 enters the top channel from the right and exits to the left. Nut 152 is then screwed on to the threads of end portion 134. End portion 136 enters the bottom channel from the left and exits to the right. Nut 154 is then applied to end portion 136 to secure the strap in place.

This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments of the example as required. However, it is to be understood that the invention can be carried out by specifically different devices and that various modifications can be accomplished without departing from the scope of the invention itself. 

What is claimed is:
 1. A storage structure comprising a plurality of hollow layers each assembled at ground level and adapted to be lifted to arranged the layers in a vertical stack, each of said plurality of hollow layers comprising a plurality of semi-circular concrete panels arranged in a circle and coupled together by tongue and groove joints, each of said semi-circular concrete panels having a thinner inner section framed by a thicker top section, a thicker bottom section, and two thicker end sections extending vertically between said thicker top section and thicker bottom section, said semi-circular concrete panels locked in a circle by a plurality of straps, each surrounding the circle and each having opposing ends coupled together by a clamp to prevent outwardly directed forces from pushing the semi-circular concrete panels out of the circle and to permit the layers to be lifted to form the vertical stack.
 2. The storage structure of claim 1 wherein the two thicker end sections each have a set of horizontally extending recesses, each of said horizontally extending recesses adapted to receive a strap of said plurality of straps when the straps surround the circle.
 3. The storage structure of claim 1 wherein said semi-circular concrete panels have at least one vertical support rib.
 4. The storage structure of claim 3 wherein the two thicker end sections and the at least one vertical support rib each have a set of horizontally extending recesses, each of said horizontally extending recesses adapted to receive a strap of said plurality of straps when the straps surround the circle.
 5. The storage structure of claim 1 wherein said straps have threaded ends and said clamp comprises (a) a block having a pair of channels adapted to permit the threaded ends of the cable to pass the block, and (b) nuts adapted to be coupled to the threaded ends of the cable.
 6. A storage structure comprising: a. a plurality of semi-circular wall panels each made of concrete and adapted to be arranged in a plurality of hollow circular layers, and said plurality of hollow circular layers adapted to be arranged in a hollow vertical stack, each of said wall panels having thinner inner section framed by (i) a thicker top portion terminating in a first horizontal planar surface, (ii) a thicker bottom portion terminating in a second horizontal planar surface, (iii) a first thicker end section terminating in a first planar end surface extending between the first and second horizontal planar surfaces, (iv) a second thicker end section terminating in a second planar end surface extending between the first and second horizontal planar surfaces, (v) a tongue extending from one of the first and second horizontal planar surfaces and a groove recessed from the other of said first and second horizontal planar surfaces, and (vi) a tongue extending from one of said first and second planar end surfaces and a groove recessed in the other of said first and second planar end surfaces; b. a plurality of hollow circular layers assembled at ground level and adapted to be lifted to form a stack of said plurality of hollow circular layers, each of said plurality of hollow circular layers comprising (i) a set of the plurality of semi-circular wall panels, (ii) first tongue and groove joints between immediately adjacent semi-circular wall panels of the set, said first tongue and groove joints each comprising a tongue extending from a second planer end surface of a semi-circular wall panel and a groove formed in a planer end surface of an immediately adjacent semi-circular wall panel, (iii) a plurality of straps surrounding the set of the plurality of semi-circular wall panels, each of said plurality of straps having a main body portion, a first end portion and a second end portion, and (iv) a plurality of clamps securing the first and second end portions of the straps together and further securing together the plurality of semi-circular wall panels of the set of semi-circular wall panels; c. a vertical stack of said hollow circular layers comprising second tongue and groove joints between immediately adjacent hollow circular layers of the stack, said second tongue and groove joints each comprising a tongue extending from a horizontal planar surface of a semi-circular wall panel of a hollow circular layer and a groove recessed in a horizontal planar surfaces of a semi-circular wall panel of an immediately adjacent hollow circular layer of the stack of said plurality of hollow circular layers.
 7. The storage structure of claim 6 wherein each of the semi-circular wall panels comprises at least one reinforcing rib.
 8. The storage structure of claim 7 wherein said at least one reinforcing rib extends vertically between the thicker top portion and the thicker bottom portion.
 9. The storage structure of claim 6 wherein each of the semi-circular wall panels comprises a plurality of reinforcing ribs extending vertically between the thicker top portion and the thicker bottom portion.
 10. The storage structure of claim 6 wherein each of the straps has its first and second end portions angled from its main body portion.
 11. The storage structure of claim 10 wherein each, of said clamps comprises a bolt extending through the first and second end portions of a strap and a nut coupled to the bolt.
 12. The storage structure of claim 6 wherein the first thicker end section and second thicker end section each have a plurality of recesses adapted to receive the straps.
 13. The storage structure of claim 7 wherein the first thicker end section, the second thicker end section and each of said at least one reinforcing rib each have a plurality of recesses adapted to receive the straps. 